1. Field of the Invention
The present invention relates to a liquid crystal display, and more particularly to a liquid crystal display capable of preventing a brace and a variable resistance lead part from contacting each other.
2. Discussion of the Related Art
Liquid crystal displays are smaller in size than cathode ray tubes and are used extensively in potable televisions and monitors of lap-top computers. Active matrix liquid crystal displays use thin film transistors (TFTs) as switching devices to display pictures corresponding to video signals (e.g., television signal) inputted to a pixel matrix.
The pixel matrix contains pixels arranged at intersections of gate lines and data lines. Each pixel within the pixel matrix includes a liquid crystal cell that controls light transmittance of a liquid crystal in accordance with a voltage level of a data signal applied from the data line. Installed at intersections of the gate and data lines, TFTs switch the data signal in response to the scanning signal (gate pulse) applied from the gate line to transmit data signals to liquid crystal cells.
Referring to FIG. 1, liquid crystal display panels typically include a plurality of pixel cells (PCE) arranged at intersections of a plurality of gate lines, GL1 to GLm, and a plurality of data lines, DL1 to DLn.
Each pixel cell includes a liquid crystal cell connected to a common voltage line and an auxiliary capacitor (Ca) connected to a corresponding preceding gate line (e.g., GL0 to GLm-1). The liquid crystal cell and the auxiliary capacitor (Ca) are selectively connected to the data lines DL1 to DLn when the TFT is turned on in response to a scanning signal on the gate lines GL1 to GLm.
Liquid crystal cells arranged adjacent one anther on the liquid crystal display panel may be charged with data signals of opposite polarities. As shown in FIG. 2A, in what is known as a dot inversion driving method, each liquid crystal cell is charged with a data signal having a polarity opposite data signals charged within adjacent liquid crystal cells. As shown in FIG. 2B, in what is known as a line inversion driving method, liquid crystal cells connected to the same gate line are charged with data signals having a polarity opposite data signals charged within liquid crystal cells connected to adjacent gate lines. As shown in FIG. 2C, in what is known as a column inversion driving method, liquid crystal cells connected to the same data line are charged with data signals having a polarity opposite that data signals charged within liquid crystal cells connected to adjacent data lines.
Referring to FIG. 3, when the liquid crystal display panel is driven by any of the dot, line, or column inversion driving methods, the polarity of the data signals applied to the liquid crystal cells is inverted at every frame about a common voltage (Vcom), used as a reference voltage. A flicker phenomenon is induced, however, when the polarity of the data signals is inverted and pictures displayed in preceding frames remain within a picture displayed in a current frame. Generally, the flicker phenomenon is induced when positive data signals and negative data signals are not symmetric about the common voltage (Vcom) (i.e., when the voltage difference between the positive data signals and the negative data signals about the common voltage is not zero).
FIGS. 4 and 5 illustrate a plan view and a section view, respectively, of a liquid crystal display capable of preventing inducement of the flicker phenomenon. The liquid crystal display includes a variable resistance lead part 20 installed according to a side mounting method.
Referring to FIGS. 4 and 5, typical liquid crystal display modules include a liquid crystal display panel 12 having an active area where a picture is to be displayed, a backlight unit 14 installed behind the liquid crystal display panel 12 for providing light to the liquid crystal display panel 12, a printed circuit board (PCB) 24 for driving the liquid crystal display panel 12, a variable resistance lead part 20 exposed at the edge of the PCB 24, a top case 16 arranged at the top of the liquid crystal display panel 12 for securing the liquid crystal display panel 12 to the backlight unit 14, and a brace 18 providing a ground potential. Mounting holes 22 are formed to secure the liquid crystal display module to a system.
Mounting holes 22 secure the liquid crystal display module via a side mounting method. Side surfaces of the liquid crystal display module are secured to the system with mounting means (e.g., screw groove) provided by the mounting holes 22 in the side surface of the liquid crystal display module. Using the side mounting method, thickness of the module may be minimized and the active area of the liquid crystal display panel may be maximized.
The liquid crystal display panel 12 is formed by bonding an upper substrate, supporting a color filter array and an alignment film (not shown), and a lower substrate, supporting a TFT array and an alignment film (not shown). The backlight unit 14 converts light generated at a light source such that light incident on the liquid crystal display panel 12 is uniform.
The PCB 24 is located at a rear of the liquid crystal display panel 12 and includes a tape carrier package TCP bent using a tape automated bonding TAB method.
By forming a hole in a front portion of the top case 16, the variable resistance lead part 20 is exposed to the surface of the top case 16. Accordingly, the variable resistance lead part 20 may be easily controlled. The variable resistance lead part 20 controls a common voltage level (e.g., approximately 3-4 V) that is applied to a common electrode in order to prevent the flicker phenomenon from being induced in the liquid crystal display module.
The top case 16 covers an edge and side surface of the liquid crystal display panel 12 in addition to optical components of the backlight unit 14.
Ground potential is supplied to the brace 18 for eliminating the buildup of static electricity within the liquid crystal display module. The brace 18 contacts and grounds the top case 16.
The PCB 24 is located behind the liquid crystal display panel 12 to reduce the outer area of the top case 16 covering the liquid crystal display panel 12. An area of the top case 16 provided in the non-display area is reduced so that the variable resistance lead part 20 contacts the brace 18. Considering that approximately 3˜4V is supplied to the variable resistance lead part 20, wherein the variable resistance lead part 20 contacts the brace 18, the variable resistance lead part 20 becomes grounded. Accordingly, the variable resistance lead part 20 fails to prevent the flicker phenomenon from being induced due to its contact with the brace 18.